Internet-based services and applications are rapidly growing and are fundamental to fulfill people's needs in areas such as communication, banking, shopping, information, education and entertainment. High performance internet access solutions are an important prerequisite. Currently, in most cases residential customers use DSL technologies (such as ADSL or VDSL) for Internet access, whereas mobile customers use cellular technologies (such as GSM, UMTS or LTE).
The maximum data rates which can be provided via DSL depend on the length of the access line. For longer distances, e.g. in rural areas, in many cases only a few Mbit/s are feasible. To mitigate limitations in the access, a bonding of multiple access links can be applied. Solutions are available in particular for business customers, e.g. bonding of multiple DSL lines [1].
It is also possible to combine access links provided by different media, such as DSL and cellular access, as for example described in [2]. This “hybrid access” is technically much more challenging than the combination of multiple links of the same media, in particular due to the high dynamics of the mobile access link (e.g. in terms of available throughput or latency) and due to the completely different access and core network architectures of existing fixed and mobile networks.
A typical available solution for a “hybrid access” is sketched in FIG. 1. It consists of multiple “hybrid access clients” (e.g. residential gateways or other devices such as desktop or laptop computers) controlled by a common “hybrid access server”. (For simplicity reasons in FIG. 1 only one client is depicted.) Each hybrid access client has at least two access interfaces, one for example for DSL access and another one for example for access to cellular networks (e.g. UMTS networks or LTE networks). The hybrid access server is located in the public Internet. It is the common anchor point which processes all data packets from/to the client when communicating with an applications host (e.g. a content server), e.g. located in the public Internet. The traffic between the hybrid access clients and the hybrid access server is controlled by distributed “hybrid access algorithms and protocols” which decide which part of the user traffic will be transmitted via which access medium. The traffic split can be done with different granularities, e.g. packet-wise splitting or distributing the different IP flows. In addition to the user traffic some control traffic generated by the hybrid access algorithms and protocols has to be transmitted via the different access channels. In many cases, tunnels between a hybrid access client and the hybrid access server are established over the different access channels (e.g. using OpenVPN), e.g. for security reasons.
More sophisticated solutions try to perform measurements of instantaneous channel parameters (see e.g. [4]) of the different access links and use these parameters as input for algorithms controlling the traffic flows. However, the measurements often show a low accuracy and produce additional traffic overhead.
The general drawback of the current hybrid access solutions, including solutions working above IP layer (e.g. “Multipath TCP” [3]) is that they work “over the top”, that means the networks between the hybrid access client and the hybrid access server are used as unknown “clouds”. Knowledge available in the access and core networks (e.g. network load, available capacity, requested or used services . . . ) is not utilized for the algorithms controlling the hybrid access. Moreover, if tunnels are used via the different links between hybrid access client and hybrid access server, it may not be possible to reach service control platforms located in the operator's core network, e.g. an IMS platform to control a “Voice over IP (VoIP)” service.